Freestyle Uniform Displacement
Basically, you want to increase the Wavelength and Amplitude of the Sinus when the camera go closer to the object. You can do that with Drivers.

On the picture below, you can see the settings for the Wavelength driver :


a variable (named dist) return the distance between Cube and Camera
we invert it (1/dist), cause we want the value to decrease when the distance increase
we multiply it by a value (*200), which define the overall amplitude.


To find the right value, you can do trial and error, or calculate it. Here you can see dist is 10.439 ; say your desired Wavelength is 20 ; 1/10.439*x = 20 -> x = 20*10.439 = more or less 200.

The method is exactly the same for Amplitude. I used (1/dist)*30.